1. Field of the Invention
The present invention relates generally to lighting device power sources such as those included within dimmable light emitting diode lamps, and in particular to a lighting device power source that provides a correct measure of the duty factor of a triac-based dimmer while powering high-efficiency lighting devices.
2. Background of the Invention
Lighting control and power supply integrated circuits (ICs) are in common use in both electronic systems and in replaceable consumer lighting devices, e.g., light-emitting-diode (LED) and compact fluorescent lamp (CFL) replacements for traditional incandescent light bulbs.
In particular, in dimmable high-efficiency replacement light bulbs, the low energy requirements of the lighting devices makes it difficult for the typical thyristor-based dimmers to operate properly, as the triac circuit that implements the typical dimmer is designed for operation with a load that requires on the order of ten times the current required by the typical high-efficiency lighting device. Therefore, dimmable high-efficiency replacement lighting device circuits must ensure that the dimmer operates properly in conjunction with the lighting devices, i.e., supplies a sufficient amount of energy and provides a needed indication of the dimming level, so that dimming of the lighting devices can be performed.
Therefore, it would be desirable to provide a dimmable high-efficiency lighting device power source circuit that provides proper operation of a triac-based dimmer circuit and also provides the proper dimming level.